Pre-doping system of electrode and pre-doping method of electrode using the same

ABSTRACT

The present invention provides a pre-doping system of an electrode and a system using the same. The pre-doping system includes: a doping means for performing a doping process where lithium ions are doped into an electrode; a measuring means for performing a measuring process where an open-circuit potential of the electrode is measured; a switch unit for selectively performing any one of the doping process and the measuring process; a controller for controlling the doping means, the measuring means, and the switch unit and acquiring the open-circuit potential of the electrode measured by the measuring means.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. Section [120, 119, 119(e)] of Korean Patent Application Serial No. 10-2010-0071934, entitled “Pre-Doping System Of Electrode And Pre-Doping Method Of Electrode Using The Same”, filed on Jul. 26, 2010, which is hereby incorporated by reference in its entirety into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pre-doping system of an electrode; and, more particularly, to a pre-doping system of an electrode and a pre-doping method for an electrode using the same.

2. Description of the Related Art

In general, an electrochemical energy storage apparatus refers to a core component of finished products essentially used in electronic appliances. Also, the electrochemical energy storage apparatus is expected to be certainly used as a high-quality energy source in renewable energy fields applicable to future electric vehicles, portable electronic devices, and so on.

An electrochemical capacitor of electrochemical energy storage apparatuses may be classified into an electrical double layer capacitor using an electrical double layer principle and a hybrid super-capacitor using electrochemical oxidation-reduction reactions.

Herein, the electrical double layer capacitor is mainly used in a field requiring high-output energy characteristics, but it has a disadvantage such as low capacitance. On the contrary, the hybrid super-capacitor has been actively researched as an alternative solution for improving capacitance characteristics of the electrical double layer capacitor. In particular, a Lithium Ion Capacitor LIC of hybrid super-capacitors may have a storage capacitance four times as large as that of the electrical double layer capacitor.

The formation of an LIC may be made by a stacking process, a welding process, a pre-processing doping process, and a sealing process. In the stacking process, anodes, separators, and cathodes in sheet shapes are stacked one on another to thereby form an electrode stacked structure. In the welding process, terminals of the anodes and the cathodes are respectively welded. In the pre-processing process, lithium ions are pre-doped into the cathodes. In the sealing process, the electrode stacked structure is sealed with aluminum.

Herein, the pre-processing process for pre-doping the lithium ions into the cathodes may be made by forming lithium metallic films on each of the uppermost layer and lowermost layer of the electrode stacked structure, and then immersing it into electrolytic solution. This pre-doping process involves charging/discharging processes several-times, the charging process being made by applying voltages to anodes and cathodes in electrolytic solution and the discharging process being made between the anodes and lithium metal. Therefore, in case of the pre-doping process, an additional device for applying external currents/voltages should be installed. In addition, it takes 20 days to uniformly dope lithium ions into the cathodes provided within the electrode stacked structure, which results in a difficulty for mass-production.

At this time, by performing the pre-doping process for pre-doping the cathodes before the stacking process, and then the stacking process for stacking the cathodes and the separators and the anodes, it is possible to shorten a time taken for the pre-doping process.

However, the number of electrodes stacked in a high-capacitance LIC becomes increased, and thus the process time lengthens in manufacturing the LIC with a limited high-capacitance. This is because each of the cathodes should be subjected to the doping process.

Also, the cathodes doped with the lithium ions are significantly sensitive to moisture and thus it is not easy to treat. Therefore, it is difficult to verify the doping level of the cathodes during the doping process and in an assembling process followed by the process, which results in limitation to reliability and mass-production of the LIC.

Thus, there was a trial to perform the pre-doping process for the cathodes before the stacking process to improve the mass-production of the LIC. However, it was impossible to actually control the pre-doping process for the cathodes.

SUMMARY OF THE INVENTION

The present invention has been proposed in order to overcome the above-described problems and it is, therefore, an object of the present invention to provide a pre-doping system of an electrode which is provided with a measuring means for measuring an open-circuit potential of an electrode to thereby control a pre-doping process of the electrode, and a pre-doping method of the electrode using the same.

In accordance with one aspect of the present invention to achieve the object, there is provided an electrode pre-doping system including: a doping means for performing a doping process where lithium ions are doped into an electrode; a measuring means for performing a measuring process where an open-circuit potential of the electrode is measured; a switch unit for selectively performing any one of the doping process and the measuring process; a controller for controlling the doping means, the measuring means, and the switch unit and acquiring the open-circuit potential of the electrode measured by the measuring means.

Also, the doping means includes: a doping bath for receiving electrolytic solution in which the electrode is immersed; and a metal which supplies the lithium ions and is immersed together with the electrode into the electrolytic solution.

Also, the system further includes a separator provided on one surface of the metal facing the electrode.

Also, the switch unit includes: one terminal connected to a common contact electrically connected to a supply source of the lithium ions; and the other terminal selectively connected to any one of a first contact and a second contact, the first contact being electrically connected to the electrode and the second contact being electrically connected to the electrode through the measuring means.

Also, the electrode includes a current collector, and an active material layer which is disposed at least one surface of the current collector and reversibly dopes or un-dopes the lithium ions.

Also, the system further includes a temperature controller for controlling a temperature of the doping means.

Also, the system further includes a heating means for heating the doping means by the temperature controller.

Also, the system further includes a moving means for inputting and outputting the electrode and the supply source of the lithium ions into and out of the doping means.

Also, the moving means includes: a carrier for seating and moving the electrode and the supply source of the lithium ions; a sliding rail for guiding movement of the carrier; and a driving unit for moving the carrier on the slide rail.

Also, the supply source of the lithium ions includes a metal containing the lithium ions, the metal being disposed to face the electrode.

In accordance with another aspect of the present invention to achieve the object, there is provided a pre-doping system of an electrode including: a doping bath for receiving electrolytic solution; a carrier for inputting and outputting an electrode and a metal into and from the electrolytic solution received in the doping bath; a sliding rail for guiding the movement of the carrier; a driving unit for moving the carrier on the slide rail; a measuring means for measuring an open-circuit potential of the electrode; and a switch unit for selectively connecting the electrode, the metal, and the measuring means.

Also, the switch unit includes: one terminal connected to a common contact electrically connected to the metal; and the other terminal selectively connected to any one of a first contact and a second contact, the first contact being electrically connected to the electrode and the second contact being electrically connected to the electrode through the measuring means.

Also, the driving unit includes: a driving motor for generating a driving force; a timing belt rotated by the driving force; and a lead screw for moving the carrier by the rotation of the timing belt.

Also, the system further includes a heating means for adjusting a temperature of the electrolytic solution, the heating means being disposed on a lower portion of the doping bath.

Also, the system further includes a display device for outputting an open-circuit potential of the electrode in real time.

Also, the display device further comprises an input device for inputting operation signals used to operate the driving unit, the measuring means, and the switch unit.

Also, the input device includes a touch panel.

Also, the system further includes a separator formed on one surface of the metal facing the electrode.

Also, the electrode includes terminals exposed from the electrolytic solution.

Also, the electrode includes a current collector, and an active material layer which is disposed at least one surface of the current collector and reversibly dopes or un-dopes the lithium ions.

In accordance with still another aspect of the present invention to achieve the object, there is provided a method for pre-doping an electrode including the steps of: immersing a metal and an electrode into electrolytic solution; doping lithium ions into the electrode from the metal; measuring an open-circuit potential of the electrode; and repeatedly performing the doping and measuring steps until the open-circuit potential of the electrode reaches a preset value.

Also, the step of measuring the open-circuit potential is performed after the doping process of the electrode is stopped.

Also, the system further includes a step of adjusting a temperature of the electrolytic solution, before the doping process of the electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic-view showing a system for pre-doping an electrode in accordance with a first embodiment of the present invention;

FIG. 2 is a cross-sectional view showing a detailed shape of the system for pre-doping the electrode in accordance with a first embodiment of the present invention;

FIG. 3 is a top view showing the system for pre-doping the electrode shown in FIG. 2; and

FIG. 4 is a flowchart showing a process of pre-doping the electrode in accordance with a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERABLE EMBODIMENTS

Embodiments of a system for pre-doping an electrode in accordance with the present invention will be described in detail with reference to the accompanying drawings. When describing them with reference to the drawings, the same or corresponding component is represented by the same reference numeral and repeated description thereof will be omitted.

FIG. 1 is a schematic view showing a system of pre-doping an electrode in accordance with a first embodiment of the present invention.

Referring to FIG. 1, a system of pre-doping an electrode 100 (hereinafter, referred to as “electrode pre-doping system 100”) in accordance with the first embodiment of the present invention may include a doping means 110, a switch unit 130, a measuring means 140, and a controller 150.

The electrode pre-doping system 100 may be used to dope lithium ions into cathodes before anodes, separators, and cathodes are stacked to manufacture an LIC.

The doping means 110 may play a role of performing a doping process for the electrode 120. The doping means 110 may include a doping bath 111 and metal 113.

Herein, the doping bath 111 may be provided with opened upper surfaces as a bath for receiving electrolytic solution 112. Thus, it is possible to input and output the electrode 120 and the metal 113 into and out of the doping bath 111 with ease. The electrolytic solution 112 plays a role of a medium for transferring lithium ions, and it may be formed of a material which makes lithium ions stable owing to non-occurrence of electrolysis at a high voltage. For example, the electrolytic solution 112 may include a solvent with dissolved lithium salt therein. As for the lithium salt, LiPF6, LiBF4, LiClO4, and so on may be exemplified. Also, as for the solvent, an organic solvent with non-proton property may be exemplified. However, the material of the electrolytic solution 112 is not limited by the embodiment of the present invention.

Also, the metal 113 may serve as a supply source of lithium ions doped into the electrode 120. That is, the metal 113 may be materials containing lithium ions, such as lithium and lithium alloy. At this time, in case where the metal 113 and the electrode 120 are short-circuited, due to a potential difference between the metal 113 and the electrode 120, the lithium ions may be doped into the electrode 120.

Herein, a separator 114 may further be disposed on one surface of the metal 113 opposed to the electrode 120. The separator 114 may play a role of preventing the metal 113 from directly contacting the electrode 120. This is because a doping process is controlled with no ease and a uniform doping process for the electrode 120 is not guaranteed as there is a possibility of performing a doping process due to direct contact between the metal 113 and the electrode 120. That is, the separator 114 may play a role of stabilizing the doping process of the electrode 120.

The switch unit 130 may play a role of selecting any one of the doping process of the electrode 120 and a measuring process of an open-circuit potential in the electrode 120. Herein, the switch unit 130 may include a relay switch. For example, the switch unit 130 may include one terminal connected to a common contact 131, and the other terminal connected selectively to any one of first and second contacts 132 and 133. At this time, the common contact 131 may be electrically connected to the metal 113. Also, the first contact 132 may be electrically connected to the electrode 120. Also, the second contact 133 may be electrically connected to the electrode 120 through the measuring means 140.

Thus, by the switching operation of the switch unit 130, the doping process by the doping means 110 or the measuring process by the measuring means 140 may be selectively performed.

The measuring means 140 measures the open-circuit potential of the electrode 120. Herein, when the electrode 120 and the metal 113 are open-circuited within the electrolytic solution 112, the open-circuit potential of the electrode 120 may be a potential value of a reference electrode (i.e. the electrode 120 measured by connecting the metal 113 to the measuring means 140) immersed within the electrolytic solution 112. Herein, the open-circuit potential of the electrode 120 may be varied according to doping amount of lithium ions doped into the electrode 120. For example, the more the lithium ions doped into the electrode 120, the lower the open-circuit potential of the electrode 120. Thus, a doping level may be verified by the open-circuit potential of the electrode 120 measured by the measuring means 140.

The controller 150 controls the doping and measuring processes and acquires information about the open-circuit potential of the electrode 120 measured by the measuring means 140. Herein, under the control of the controller 150, the switch unit 130 connected to the controller 150 may selectively perform any one of the doping process and the measuring process according to control commands.

Also, the controller 150 is connected to the measuring means 140 to thereby apply measuring signals for measuring the open-circuit potential of the electrode 120 to the measuring means 140. Also, the controller 150 may acquire data measured from the measuring means 140 according to measuring signals, that is, information on the open-circuit potential of the electrode 120.

In addition, the electrode pre-doping system 100 may further include a temperature controller 160 for controlling the temperature of the doping means 110, that is, the temperature of the electrolytic solution 112 received in the doping bath 111, so as to control the speed of the doping process. This means that since the doping speed is influenced by the temperature of the electrolytic solution 112, the doping speed can be controlled according to the temperature of the electrolytic solution 112.

The temperature controller 160 may be connected to the controller 150. At this time, the temperature controller 160 may control the temperature of the doping means 110 according to temperature control commands provided from the controller 150. Also, the temperature controller 160 may provide the temperature information of the doping means 110 to the controller 150. Upon receiving the temperature information, the controller 150 may generate temperature control commands for the temperature controller 160 on the basis of the received temperature information of the doping means 110.

Also, the electrode pre-doping system 100 may further include a moving means for inputting and outputting the electrode 120 into and from the doping means 110. Herein, the moving means may input the metal 113, together with the electrode 120, within the doping means 110. The moving means may include a carrier, a sliding rail, and a driving unit. The carrier moves the electrode 120 seated thereon, and the sliding rail guides the carrier to be moved. The driving unit moves the carrier on the sliding.

Also, the electrode pre-doping system 100 may further include a display device for real-time outputting the open-circuit potential of the electrode 120 after receiving the open-circuit potential from the controller 150.

Also, the electrode pre-doping system 100 may further include an input device for receiving operation signals inputted for operation of the electrode pre-doping system 100. Therefore, it is possible for a worker to operate the electrode pre-doping system through the input device. Herein, the input device may be in a shape of a touch panel installed in the display device.

Meanwhile, the electrode 120 may have a cathode of the lithium ion capacitor.

The electrode 120 may include a current collector 121 and an active material layer 122 which is disposed on at least one surface of the current collector 121 and is capable of reversibly doping or un-doping the lithium ions. Herein, the current collector 121 may be formed in a metal mesh or a metal foil. At this time, the metal may include any one of Cu and Ni, but the present invention is not limited thereto. Also, the active material layer 122 may include a carbon material capable of reversibly doping and un-doping lithium ions, e.g., graphite.

In addition, the electrode 120 may further include a terminal 123 which extends from one end of the current collector 121 to be electrically connected to an external circuit unit. At this time, the terminal 123 may be protruded from the current collector 121. That is, the terminal 123 may be integrated with the current collector 121.

Herein, in case where the electrode 120 is immersed into the electrolytic solution 112 for its doping process, the terminal 123 of the electrode 120 may be exposed. This is because when the terminal 123 is contaminated by the electrolytic solution 112, fusion failure may occur during a fusion process of the terminal 123 performed to form the lithium ion capacitor.

Although it has been shown and illustrated in the embodiment of the present invention that the pre-doping process of the electrode 120 is performed for one electrode 120, the present invention is not limited thereto. Also, a plurality of electrodes may be individually subjected to the pre-doping process.

As in the embodiment of the present invention, in case where lithium ions are doped into the electrode 120 by using the electrode pre-doping system 100, it is possible to monitor a doping level of the electrode 120 in real time. Therefore, it is possible to prevent the actual doping amount from being less than or greater than a preset doping amount. Thus, in case where a pre-doped cathode by the electrode pre-doping system 100 is used to manufacture a lithium ion capacitor, it is possible to improve reliability and cycle characteristics of the lithium ion capacitor.

Also, by the electrode pre-doping system 100 of the present invention, it is possible to verify the doping level of the electrode 120 in real time, thereby controlling the pre-doping process of the electrode 120. Thus, the electrode pre-doping system 100 may be easily applied for mass-production through a process design. Also, the electrode pre-doping system 100 may control the speed of the doping process by be additionally provided with the temperature controller 160.

FIG. 2 is a cross-sectional view showing a detailed shape of the electrode pre-doping system in accordance with the first embodiment of the present invention.

FIG. 3 is a top view showing the electrode pre-doping system shown in FIG. 2.

Referring to FIGS. 2 and 3, the electrode pre-doping system 100 in accordance with the first embodiment of the present invention may include the doping bath 111, a carrier 210, a sliding rail 220, a driving unit 230, the measuring means 140, and the switch unit 130.

The doping bath 111 may receive the electrolytic solution 112 for transferring the lithium ions. The doping bath 111 may be provided with opened upper surfaces. At this time, the electrode 120 and the metal 113 inputted into the doping bath 111 through the opened upper surfaces may be immersed into the active material layer 122 received in the doping bath 111.

The doping bath 111 may be fixed by a frame 300 disposed at an external side.

The carrier 210 may play a role of moving the electrode 120 seated thereon. Herein, the electrode 120 may include a current collector 121 and an active material layer 122 which is disposed on at least one surface of the current collector 121 and is capable of reversibly doping and un-doping lithium ions. In addition, the electrode 120 may further include the terminal 123 which extends from one end of the current collector 121 to be electrically connected to an external circuit unit.

The carrier 210 may move the electrode 120 together with the metal seated thereon. Herein, the metal 113 may serve as a supply source of lithium ions and may be formed of a material, such as lithium and lithium alloy. In addition to this, a separator is further provided on one surface of the metal 113 opposed to the electrode 120, thereby stabilizing the doping process.

The carrier 210 may seat the metal 113 and the active material layer 122 of the electrode 120 to face each other. For example, in case where the electrode 120 includes the current collector 121 whose both sides are provided with the active material layer 122, the metal 113 may be disposed to face each of the sides of the electrode 120.

In order to perform the doping process of the electrode 120, the carrier 210 may make the electrode 120 and the metal 113 immersed into the electrolytic solution 112 received in the doping bath 111 by being lowered from the upper portion to the lower portion of the doping bath 111. At this time, the terminal 123 of the electrode 120 is allowed to be exposed from the electrolytic solution 112, so as to prevent the terminal 123 of the electrode 120 from being contaminated by the electrolytic solution 112. Also, in case where the doping process of the electrode 120 is completely performed, the carrier 210 is raised from the downside to the upside of the doping bath 111, so that it is possible to output the electrode 120 and the metal 113 from the electrolytic solution 112.

The sliding rail 220 may be connected to the carrier 210 and may be disposed on an external side of the doping bath 111. At this time, the sliding rail 220 may be fixed by the frame 300. Herein, the sliding rail 220 may play a role of guiding movement of the carrier 210.

The driving unit 230 may be fixed by the frame 300 disposed on an external side of the doping bath 111. Herein, the driving unit 230 may include a driving motor 231, a timing belt 232, and a lead screw 233. The driving motor 231 forms a driving force, and the timing belt 232 is rotated by the driving force provided from the driving motor 231. The lead screw 233 lifts and lowers the carrier 210 by rotation of the timing belt 232 connected to the timing belt 232. At this time, the lead screw 233 and the sliding rail 220 may be fixed by the frame 300 disposed at an external side of the doping bath 111 with a parallel relation to each other.

The measuring means 140 may be disposed on an external side of the doping bath 111. Herein, the measuring means 140 is disposed on the external side of the frame 300. However, preferably, the measuring means 140 may be laid inside the frame 300.

The measuring means 140 may play a role of measuring the open-circuit potential of the electrode 120 in order to verify the doping level of the electrode 120 while the electrode 120 is being subjected to the doping process. Herein, the measuring means 140 may perform the measuring process after stopping the doping process of the electrode 120. The measuring means 140 may use the metal 113 as a reference electrode. At this time, the measuring means 140 is electrically connected to the metal 113 to thereby measure the potential of the electrode 120 immersed into the electrolytic solution 112.

Thereafter, after the measuring process is completely performed by the measuring means 140, the electrode 120 and the metal 113 are made short-circuited to re-perform a doping process of the electrode 120. Thus, the open-circuit potential of the electrode 120 is measured during the doping process of the electrode 120, so that it is possible to verify the doping level in real time.

It has been shown that the switch unit 130 is disposed at an external side of the frame 300. However, preferably, the switch unit 130 may be laid inside the frame 300, together with the measuring means 140.

The switch unit 130 may selectively connect the electrode 120, the metal 113, and the measuring means 140. That is, the switch unit 130 may allow the electrode pre-doping system 100 to selectively perform the doping process or the measuring process. Herein, the switch unit 130 may be a relay switch. For example, the switch unit 130 may include one terminal connected to the common contact 131, and the other terminal connected selectively to any one of the first and second contacts 132 and 133. At this time, the common contact 131 may be electrically connected to the metal 113. Also, the first contact 132 may be electrically connected to the electrode 120, and the second contact 133 may be electrically connected to the electrode 120 through the measuring means 140. Thus, the switching operation of the switch unit 130 may allow the doping process or the measuring process to be selectively performed.

In addition to this, the electrode pre-doping system 100 may further include a display device 400 for real-time outputting the open-circuit potential of the electrode 120 measured by the measuring means 140. It is possible for a worker to control the pre-doping process of the electrode 120 by monitoring the open-circuit potential of the electrode 120 provided from the display device 400.

Also, the electrode pre-doping system 100 may further include an input divide for inputting operation signals used to operate the driving unit 230, the measuring means 140, and the switch unit 130. Herein, the input device may be implemented in a touch panel provided in the display device 400.

Also, the display device 400 may output control signals for controlling the driving unit 230, the measuring means 140, and the switch unit 130 according to the operation signals by being provided with the controller, that is, a Micro Control Unit (MCU).

Also, a heating means 170 may further be disposed on a lower portion of the doping bath 111. The heating means 170 may maximize the doping process of the electrode 120 by increasing the temperature of the electrolytic solution 112 received in the doping bath 111 up to a predetermined temperature. Herein, the predetermined temperature may be a temperature of 60° C., but the present invention is not limited thereto.

Also, the electrode pre-doping system 100 may further include the temperature controller 160 which is connected to the heating means 170 to control the heating means 170. Herein, the temperature controller 160 controls the heating means 170 according to the temperature control commands provided from the MCU, thereby adjusting the temperature of the electrolytic solution 112. Also, the temperature controller 160 may provide the temperature of the electrolytic solution 112 to the MCU. At this time, based on the information about the temperature conditions of the electrolytic solution, the MCU can provide the temperature control commands to the temperature controller 160. Thus, it is possible to adjust the doping process speed of the electrode 120 according to the doping level of the electrode 120, which results in an increase of production's efficiency for the electrode 120.

Hereinafter, with reference to FIG. 4, an electrode pre-doping process in accordance with a second embodiment of the present invention will be described in more detail.

FIG. 4 is a flowchart showing a process of pre-doping the electrode in accordance with a second embodiment of the present invention.

Referring to FIG. 4, in order to perform the electrode pre-doping process in accordance with a second embodiment of the present invention, first, it is judged whether the temperature of the electrolytic solution corresponds to a temperature set to efficiently perform the electrode pre-doping process. Although it is assumed that the preset temperature of the electrolytic solution is a temperature of 60° C., the present invention is not limited thereto. The preset temperature of the electrolytic solution may be changed depending on process factors of the electrode pre-doping process, for example, electrode's shape, electrode's doping level, the kind of electrolytic solution, and so on. (step S10).

Herein, when it is judged that the temperature of the electrolytic solution fails to reach the preset temperature, the temperature of the electrolytic solution is controlled. At this time, the temperature of the electrolytic solution may be controlled through the heating means disposed on the lower portion of the doping bath receiving the electrolytic solution (step S11). Thereafter, when the temperature of the electrolytic solution is controlled by the heating means, the step S10 is again performed.

In step S10, it is judged whether the temperature of the electrolytic solution reaches the preset temperature. When it is judged that the temperature of the electrolytic solution reaches the preset temperature, the metal and the electrode are immersed into the electrolytic solution. Herein, the metal may play a role of a supply source of lithium ions, as a metal containing the lithium ions. At this time, the metal and the active material layer of the electrode may be disposed to face each other (step S20).

The metal and the electrode immersed into the electrolytic solution are made short-circuited. Due to the potential difference between the metal and the electrode, the lithium ions of the metal may be doped into the electrode. A process for doping the lithium ions into the electrode is performed (step S30).

The doping process, that is, short-circuit of the metal and the electrode, are maintained until a set time (step S40), and then the metal and the electrode are made open-circuited. The open-circuit between the metal and the electrode may allow the doping process of the electrode to be stopped (step S50).

After the metal and the electrode are made open-circuited, the open-circuit potential of the electrode is measured. Herein, the open-circuit potential of the electrode may be measured by using the metal as the reference electrode. At this time, the open-circuit potential of the electrode may be reduced depending on the doping amount of the electrode. That is, by measuring the open-circuit potential of the electrode, it is possible to verify the doping level of the electrode (step S60).

It is judged whether the open-circuit potential of the electrode coincides with a preset open-circuit potential, after the open-circuit potential of the electrode is measured (step S70).

Herein, when it is judged that the open-circuit potential of the electrode fails to reach the preset open-circuit potential of the electrode, the following steps are repeatedly performed. The steps includes the steps of making the electrode and the metal short-circuited (step S30), keeping the electrode and the metal short-circuited for a predetermined time (step S40), making the electrode and the metal open-circuited (step S50), and measuring the open-circuit potential of the electrode (step S60).

When it is judged that the open-circuit potential of the electrode reaches the preset open-circuit potential of the electrode, the electrode is outputted from the electrolytic solution (step S80), thereby terminating the electrode pre-doping process. At this time, the metal may be outputted together with the electrode from the electrolytic solution.

Therefore, as in the embodiment of the present invention, in the electrode pre-doping process, the open-circuit potential of the electrode is measured, so that it is possible to verify the doping level of the electrode on real time during the doping process.

The electrode pre-doping system according to the present invention is provided with the measuring means for measuring the open-circuit potential of the electrode, so that it is possible to verify the doping level of the electrode. Therefore, it is possible to improve reliability and cycle characteristics of the LIC.

Also, the electrode pre-doping system according to the present invention is provided with the measuring means to thereby control the pre-doping process of the electrode, so that it is possible to be applicable to mass-production through a process-design.

Also, the electrode pre-doping system according to the present invention is further provided with the temperature controller, so that it is possible to control the speed of the doping process.

As described above, although the preferable embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that substitutions, modifications and variations may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents. 

1. A pre-doping system of an electrode comprising: a doping means for performing a doping process where lithium ions are doped into an electrode; a measuring means for performing a measuring process where an open-circuit potential of the electrode is measured; a switch unit for selectively performing any one of the doping process and the measuring process; and a controller for controlling the doping means, the measuring means, and the switch unit and acquiring the open-circuit potential of the electrode measured by the measuring means.
 2. The pre-doping system of an electrode according to claim 1, wherein the doping means comprises: a doping bath for receiving electrolytic solution in which the electrode is immersed; and a metal which supplies the lithium ions and is immersed together with the electrode into the electrolytic solution.
 3. The pre-doping system of an electrode according to claim 2, further comprising a separator provided on one surface of the metal facing the electrode.
 4. The pre-doping system of an electrode according to claim 1, wherein the switch unit comprises: one terminal connected to a common contact electrically connected to a supply source of the lithium ions; and the other terminal selectively connected to any one of a first contact and a second contact, the first contact being electrically connected to the electrode and the second contact being electrically connected to the electrode through the measuring means.
 5. The pre-doping system of an electrode according to claim 1, wherein the electrode includes a current collector and an active material layer which is disposed at least one surface of the current collector and reversibly dopes or un-dopes the lithium ions.
 6. The pre-doping system of an electrode according to claim 1, further comprising a temperature controller for controlling a temperature of the doping means.
 7. The pre-doping system of an electrode according to claim 6, further comprising a heating means for heating the doping means by the temperature controller.
 8. The pre-doping system of an electrode according to claim 1, further comprising a moving means for inputting and outputting the electrode and the supply source of the lithium ions into and out of the doping means.
 9. The pre-doping system of an electrode according to claim 8, wherein the moving means comprises: a carrier for seating and moving the electrode and the supply source of the lithium ions; a sliding rail for guiding movement of the carrier; and a driving unit for moving the carrier on the slide rail.
 10. The pre-doping system of an electrode according to claim 1, wherein the supply source of the lithium ions include a metal containing the lithium ions, the metal being disposed to face the electrode.
 11. A pre-doping system of an electrode comprising: a doping bath for receiving electrolytic solution; a carrier for inputting and outputting an electrode and a metal into and from the electrolytic solution received in the doping bath; a sliding rail for guiding the movement of the carrier; a driving unit for moving the carrier on the slide rail; a measuring means for measuring an open-circuit potential of the electrode; and a switch unit for selectively connecting the electrode, the metal, and the measuring means.
 12. The pre-doping system of an electrode according to claim 11, wherein the switch unit comprises: one terminal connected to a common contact electrically connected to the metal; and the other terminal selectively connected to any one of a first contact and a second contact, the first contact being electrically connected to the electrode and the second contact being electrically connected to the electrode through the measuring means.
 13. The pre-doping system of an electrode according to claim 11, wherein the driving unit comprises: a driving motor for generating a driving force; a timing belt rotated by the driving force; and a lead screw for moving the carrier by the rotation of the timing belt.
 14. The pre-doping system of an electrode according to claim 11, further comprising a heating means for adjusting a temperature of the electrolytic solution, the heating means being disposed on a lower portion of the doping bath.
 15. The pre-doping system of an electrode according to claim 11, further comprising a display device for outputting an open-circuit potential of the electrode in real time.
 16. The pre-doping system of an electrode according to claim 15, wherein the display device further comprises an input device for inputting operation signals used to operate the driving unit, the measuring means, and the switch unit.
 17. The pre-doping system of an electrode according to claim 16, wherein the input device comprise a touch panel.
 18. The pre-doping system of an electrode according to claim 11, further comprising a separator formed on one surface of the metal facing the electrode.
 19. The pre-doping system of an electrode according to claim 11, wherein the electrode includes terminals exposed from the electrolytic solution.
 20. The pre-doping system of an electrode according to claim 11, wherein the electrode includes a current collector, and an active material layer which is disposed at least one surface of the current collector and reversibly dopes or un-dopes the lithium ions.
 21. A method for pre-doping an electrode comprising: immersing a metal and an electrode into electrolytic solution; doping lithium ions into the electrode from the metal; measuring an open-circuit potential of the electrode; and repeatedly performing the doping and measuring steps until the open-circuit potential of the electrode reaches a preset value.
 22. The method for pre-doping an electrode according to claim 21, wherein the step of measuring the open-circuit potential is performed after the doping process of the electrode is stopped.
 23. The method for pre-doping an electrode according to claim 21, further comprising a step of adjusting a temperature of the electrolytic solution, before the doping process of the electrode. 